The Smart Coaster is an intelligent coaster for your beverages. It recognizes the different types of beverages placed on top of it, with a cocktail the Smart Coaster glows in some atmospheric and slowly changing colors. If you place a cup of hot tea on it, it automatically starts a special tea timer program which shows you, when the tea is ready to drink. If the glass is empty or filled with a cold drink the Smart Coaster glows blue, if the drink within the glass is hot, it glows red.
The Smart Coaster uses a LED strip with 23 RGB LEDs, each driven by a WS2812 chip, to glow in different colors. It contains a self-made pressure sensor based on Velostat, by which it recognizes the weights of different types of glasses. Additionally a Texas Instruments TMP006 temperature sensor is placed with the coaster. This sensor detect fast changes of the temperature of the glass without the need to touch the object. For this purpose the TMP006 uses a uses a thermopile to absorb the infrared energy emitted from the glass and uses the corresponding change in thermopile voltage to determine the glass temperature. By matching these sensor values with predefined profiles the Smart Coaster differentiates between different glasses and beverages.
This instruction allows to build 2 different variants of the Smart Coaster. The first variant uses only 3D printed parts, the second variants replaces some printed parts with acrylic glass and involves therefore some additional work. It is highly recommended to build the first variant, since some parts for the Smart Coaster have to be printed in 3D.
Don't be confused, the pictures in this instructable are showing my first prototype. I used laser cut parts instead of 3d printed parts. But the build process is nearly the same. If you use 3D Printed parts you can leave out some instructions of this step. Whenever i mention acrylic glass discs they represent also the 3d printed bottom parts.
Bill of materials:
1 x Arduino Mini Pro
1 x Adafruit TMP006 Breakout
1 x LED Strip WS2812 with 23 LED’s
1 x 3D printed parts (Thingiverse)
1 x resistor 2.7 KOhm
1 x 6x6cm Velostat
1 x 3,7V 250 mAh LiPo battery (lady bug)
1 x wire
1 x insulating tape
only used when NOT building the pure 3d printed variant:
1 x circle Ø11 cm of normal white paper
1 x ring (5mm width) Ø11 cm of heavy paper or cardboard
1 x 5 mm thick disc of acrylic glass Ø11 cm
1 x 3 mm thick disc of acrylic glass Ø 11 cm
Used tools and devices:
1 x 3D printer
1 x dremel (multifunction rotary tool)
1 x hot melt glue gun
1 x solder iron
1 x FTDI breakout
1 x Cutter
1 x scissors
1 x Arduino IDE
time and affort:
2 - 4 hours